sht1x.h

SHT10/SHT11/SHT15 Device Driver.

enum sht1x_conf_t
SHT1X_CONF_LOW_RESOLUTION = 0x01
Use 8/12 bit resolution instead of 12/14 bit for temp/hum.
SHT1X_CONF_SKIP_CALIBRATION = 0x02
Don’t upload calibration data to register to safe 10 millisec.
SHT1X_CONF_ENABLE_HEATER = 0x04
Waste 8mA at 5V to increase the sensor temperature up to 10°C.
SHT1X_CONF_SKIP_CRC = 0x08
Skip the CRC check (and reading the CRC byte) to safe time.
enum sht1x_vdd_t
SHT1X_VDD_5_0V = 0
SHT1X_VDD_4_0V = 1
SHT1X_VDD_3_5V = 2
SHT1X_VDD_3_0V = 3
SHT1X_VDD_2_5V = 4
int sht1x_init(sht1x_dev_t * dev, const sht1x_params_t * params)

Initialize the SHT10/11/15 sensor.

Parameters

dev:SHT1X sensor to initialize
params:Information on how the SHT1X is connected to the board

Parameters

0:Success
-EIO:IO failure (gpio_init() failed)
-EPROTO:Sensor did not acknowledge reset command

int16_t sht1x_temperature(const sht1x_dev_t * dev, uint16_t raw)

Calculate the temperature from the raw input.

Note

This internal function is exposed for unit tests

Parameters

dev:Device from which the raw value was received
raw:The raw (unprocessed) temperature value

Parameters

INT16_MIN:Passed NULL for parameter dev or dev->vdd

Return values

  • The correct temperature in E-02 °C
int16_t sht1x_humidity(const sht1x_dev_t * dev, uint16_t raw, int16_t temp)

Calculate the relative humidity from the raw input.

Note

This internal function is exposed for unit tests

Parameters

dev:Device from which the raw value was received
raw:The raw (unprocessed) temperature value
temp:The temperature at which the humidity was measure in E-02 °C

Parameters

-1:Passed NULL for parameter dev

Return values

  • The correct temperature in E-02 %
int sht1x_read(const sht1x_dev_t * dev, int16_t * temp, int16_t * hum)

Read the current temperature.

Parameters

dev:SHT1X sensor to read
temp:Store the measured temperature in E-02 °C here
hum:Store the measured relative humidity in E-02 % here

Parameters

0:Success
-EIO:IO failure (gpio_init() failed)
-EBADMSG:CRC-8 checksum didn’t match (> Retry)
-EINVAL:Passed NULL for dev or for both temp and hum
-EBADMSG:CRC checksum didn’t match
-ECANCELED:Measurement timed out
-EPROTO:Sensor did not acknowledge command
For either temp or hum NULL can be passed, if only one value is of interest. Passing NULL for hum speeds up the communication, but passing NULL for temp does not. The temperature value is required to calculate the relative humidity from the raw input. So the temperature is measured in any case, it is just not returned if temp is NULL.

int sht1x_configure(sht1x_dev_t * dev, sht1x.h::sht1x_conf_t conf)

Apply the given configuration (= status byte) to.

Parameters

dev:SHT1X device to configure
conf:Configuration to apply

Parameters

0:Configuration applied
-EINVAL:Called with dev == NULL
-EIO:I/O error (gpio_init() failed)
-EPROTO:Sensor did not acknowledge command
-ECANCELED:Sensor did not apply configuration
-EBADMSG:CRC checksum error while verifying uploaded configuration

int sht1x_read_status(sht1x_dev_t * dev, uint8_t * status)

Read the status byte of an SHT1X sensor.

Parameters

dev:SHT1X device to receive the status from
status:Store the received status byte here

Parameters

0:Configuration applied
-EINVAL:Called with dev == NULL
-EIO:I/O error (gpio_init() failed)
-EPROTO:Sensor did not acknowledge command
-EBADMSG:CRC checksum didn’t match

int sht1x_reset(sht1x_dev_t * dev)

Reset the sensor’s configuration to default values.

Parameters

dev:SHT1X device to reset

Parameters

0:Reset successful
-EINVAL:Called with dev == NULL
-EIO:I/O error (gpio_init() failed)
-EPROTO:Sensor did not acknowledge reset command

struct sht1x_dev_t

SHT10/11/15 temperature humidity sensor.

gpio.h::gpio_t clk

GPIO connected to the clock pin of the SHT1X.

gpio.h::gpio_t data

GPIO connected to the data pin of the SHT1X.

int16_t temp_off

Offset to add to the measured temperature.

int16_t hum_off

Offset to add to the measured humidity.

uint8_t conf

Status byte (containing configuration) of the SHT1X.

uint8_t vdd

Supply voltage of the SHT1X (as sht1x_vdd_t)

struct sht1x_params_t

Parameters required to set up the SHT10/11/15 device driver.

gpio.h::gpio_t clk

GPIO connected to the clock pin of the SHT1X.

gpio.h::gpio_t data

GPIO connected to the data pin of the SHT1X.

sht1x.h::sht1x_vdd_t vdd

The supply voltage of the SHT1X.